vb6 - 如何检查 key 是否存在于集合中

Question

我想在visual basic 6.0中检查集合变量是否包含 key
下面是我拥有的集合变量

pcolFields As Collection

我想检查它是否包含字段 Event_Code。我正在按如下方式执行此操作，但它对我不起作用。

    If IsMissing(pcolFields("Event_Code")) = False Then
        'Do Something
    End If

Answer 1

这是一个带有 try-catch 的示例解决方案:

Private Function IsMissing(col As Collection, field As String)
On Error GoTo IsMissingError
    Dim val As Variant
    val = col(field)
    IsMissing = False
    Exit Function
IsMissingError:
    IsMissing = True
End Function

像这样使用它:

Private Sub Form_Load()
    Dim x As New Collection
    x.Add "val1", "key1"

    Dim testkey As String
    testkey = "key2"
    If IsMissing(x, testkey) Then
        Debug.Print "Key is Missing"
    Else
        Debug.Print "Val is " + x(testkey)
    End If

    Exit Sub
End Sub

您还可以尝试实现或子类化集合并添加“具有”功能